And the reason why you're "feeling" it has 2000mAh, is probably because in real life use, the current actually keeps dropping following the battery voltage (assuming normal linear driver).
A discharge test will keep pulling 1A regardless the voltage drop, until the battery drops below the preset target voltage.
How can you tell the difference between the UF 3000 "protected" and non protected cells? I purchased a headlamp that came with two UF 3000s that (surprise, surprise) seem to have significantly different charge times. The batteries are used in a parallel configuration. I am guessing that this will also translate to a significant difference in capacity. I am trying to figure out what I want to do with them:
1. Recycle them? They are brand new and that seems like a waste.
2. Buy 2 pairs of Panny 3400s and just use these if I forget to charge the unused Pannys.
3. Buy 1 pair of Panny 3400s and rotate these with the Pannys.
1. Those cells usually are waste.. ;)
Protected cells usually have a bump at the lower end like so:
I would get rid of all Ultrafire cells and get some decent ones. Which ones depends on your light.
They claim to be "protected" and they are longer than 65 mm. I held my calipers parallel to the button (but not contacting it - I don't want to risk shorting them). It appears to be about 69 mm long. That appears to match w/the FastTech specs for the protected cell. It looks like the Panny NCR18650B Protected cells are a physical match. I'm going to get a couple of pairs of those, a Nitecore charger, and maybe something to do controlled discharges on.
Again: those Panasonic cells might not be the best choice for your application.
The Panasonic cells are a physical match, high capacity, and are well reviewed. Am I missing something?
Yes, their discharge curve is flatter than some other cells, so they probably wont last as long/provide as much light as some other cells might. Of course, great cells, but not the perfect choice for any condition.
What cell do you recommend? I am new to this. Even though I have purchased the Pannys, I would be more than willing to have another matched set ...
Depends on your light or more specific: the driver. There might be better choices, but there dont have to be.
The light is a Cree XM-L T6. The driver? No idea. I'm assuming its the cheapest generic driver sourced out of the cheapest country in the world. The maker is supposedly a company called ePathDirect. Unfortunately, it is just an Amazon construct, so I have no idea where they sourced it from. It is so generic that the headband says "Cree" on it and the battery pack says "LED Headlight".
Got a link? Did you measure how many amps it draws? Do you have a multimeter?
I'm starting to hijack this thread w/all my questions. Sorry - I hate to do that 
. I actually have a thread set up over in the headlamp section https://budgetlightforum.com/t/-/14338. I hope you will be kind enough to continue helping me in that thread.
I greatly appreciate the tests of bad as well as good. Some lights come with batteries, such as my Ultrafire 501b, and the batteries are Ultrafire. It is good to know about various batteries. I have not purchased any Ultrafire, but have purchased some Trustfire flames. I don’t know any better, and the Trustfires seem OK to me. I did buy some Panasonic from Fast tech.
Not sure how I will notice the fact that they are better.
Thanks for the test HKJ.
Jerry